1. Field of Invention
The invention relates to an electrical series terminal, with a terminal housing, with at least two conductor connecting elements located in it, and with at least two current busses, the first end regions of which are each assigned to a conductor connecting element and the second end regions of which together form an elastic contact region for accommodating the contact plug of a test plug, the second end regions in the uninserted state of the contact plug making contact in the contact region so that the two conductor connecting elements are electrically connected to one another via the two current busses.
In addition, the invention relates to a test plug for insertion into an electrical series terminal, with an insulating housing and a contact plug, the contact plug having two terminal contacts which are arranged in succession in the lengthwise direction of the test plug and which are separated from one another by an insulating crosspiece. Finally, the invention also relates to a test terminal block comprised of a host of series terminals located next to one another and of a plurality of test plugs.
2. Description of Related Art
Electrical series terminals have been known for decades and have been used millions of times in the wiring of electrical systems and devices. The terminals are generally locked onto support rails which, for their part, are often located in a control cabinet. The conductor connecting elements in series terminals are mainly screw terminals or tension spring terminals. The clamping principle for tension spring terminals is similar to that of screw technology. While in the screw terminal a tension sleeve pulls the lead against the current bus by the actuation of the terminal screw, in the tension spring terminal this task is assumed by the tension spring. In addition, however, also insulation-piercing connecting devices or leg spring terminals can be used.
Moreover, electrical series terminals can be distinguished according to the number of conductor connecting elements. The basic type of series terminal has two conductor connecting elements which are connected to one another via a current bus; in addition however there are also series terminals with three, four or more conductor connecting elements. These series terminals, depending on their construction, are called three-lead or four-lead terminals and two-tier or three-tier terminals.
Electrical terminals are generally connecting terminals so that they have at least two conductor connecting elements which are electrically connected to one another via an electrically conductive connecting bar, the current bus. In addition to this basic type of series terminal which is often also called a feed-through terminal, there are numerous different series terminal types which are specially matched to the respective applications (see, Phoenix Contact Katalog Series terminals CLIPLINE 2005, pages 4-10). Examples are protective-conductor terminals, isolating blade terminals, and installation terminals.
In switching, measurement and control engineering, feed-through terminals with a separation possibility are the standard. The separation possibility implemented in the electrical series terminal, i.e., the separation site provided in the current bus, makes it possible to insert different plugs with different functions into the terminal housing of the series terminal which then make contact with the current bus at the separation site. In addition to simple disconnect plugs or feed-through connectors, the plugs can also be especially test plugs which can have special components and which enable checking of proper operation of the circuit connected to the series terminal.
Since the electrical series terminals are generally made disk-shaped, they are generally mated with several other electrical series terminals to form a terminal block. Then, a number of test plugs which corresponds to the number of series terminals can be inserted into such a terminal block.
A device is disclosed by German Patent Application 10 2005 025 108 B3 for testing a protective, measurement or counting means, for example, a network short relay of a high voltage or medium voltage system which has a pole strip which can be connected to the electrical means with several successively arranged pole openings and a plug block with a number of pole tongues which corresponds to the number of pole openings. An individual pole strip module of the pole strip consists of a housing in which two jacks for connection to the system and spring-loaded contact clips which are connected to the jacks are located. The two contact clips can make contact with the pole tongue of the plug, the pole tongue of the plug having two pole crosspieces which are separated from one another by an insulating crosspiece. The insulating crosspiece together with the corresponding pole opening in the pole strip module produce polarization which ensures that only one plug with a certain pole tongue can be inserted into a certain pole opening of a pole strip.
In the uninserted state of the plug or the pole tongue into the pole strip, the two contact clips make contact with one another so that the two jacks are connected to one another in an electrically conductive manner and a current can flow via a connected pole strip. If, conversely, the plug is completely inserted into the pole opening with its pole tongue, the two contact strips are electrically separated from one another and the current flow is routed via the plug, so that a test process can be carried out. In an intermediate stage—when the pole tongue of the plug is inserted into the pole opening—the two pole crosspieces make electrical contact with the two contact strips without the two contact strips already being separated from one another. However, the current flowing via the plug, in this case, is strongly dependent on how exactly the pole tongue of the plug is inserted into the pole opening of the pole strips, and slight tilting of the plug can lead to the two contact strips not making contact with the two pole crosspieces of the pole tongue at the same time.